GM Service Manual Online
For 1990-2009 cars only
  1. Check for rear position sensor DTCs (C1762 and C1763).
  2. Important: If DTCs are present, correct the condition before continuing.

  3. The vehicle must be on a level surface with doors closed, and with no passengers or extra weight in car.
  4. Connect the scan tool to the Data Line Connector (DLC).
  5. Turn the Ignition ON with the engine off.
  6. Check the rear CVRSS position sensor values using the scan tool to be sure they are within range. If not, check for bent CVRSS position sensor brackets or disconnected sensors.